ci: add lint workflow for lua (#89)

* ci: add lint workflow for lua

* fix: use correct path

* fix: actually set path

.github/workflows/validate-lua.yml

@@ -0,0 +1,37 @@
+name: validate-lua
+
+on:
+  push:
+    paths:
+      - 'lua/**'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+  stylua:
+    name: stylua
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: JohnnyMorganz/stylua-action@v2
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          version: latest
+          args: --color always --check .
+
+  luacheck:
+    name: Luacheck
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Prepare
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y luarocks
+          sudo luarocks install luacheck
+
+      - name: Lint
+        run: luacheck lua --globals vim